We present results from three-dimensional simulations of the flow induced by transient acceleration (g-jitter) in microgravity crystal growth. Transient accelerations in both axial and transverse directions are considered for a simple prototype of a vertical Bridgman crystal growth system. We also consider the effects of applying a steady magnetic field in axial or transverse directions to suppress the flow. In most cases, application of a magnetic field suppresses flow oscillations, but for transverse jitter at intermediate frequencies, flow oscillations are increased. This counter-intuitive effect is a dynamic one, in which boundary layer formation under the influence of a magnetic field shortens the time scale of momentum transfer, allowing the flow to respond more quickly to the time variation of acceleration. The effect of the magnetic field on an enclosed flow with electrically insulating boundary conditions is to preferentially suppress the velocity component tangential to the magnetic field. The ability to filter a single velocity component by application of a specified magnetic field could be useful for simultaneously improving both axial and radial segregation in semiconductor crystal growth.
Bibliographical noteFunding Information:
This work was supported in part by the Microgravity Sciences Program of the National Aeronautics and Space Administration (NASA/NAG8-1474), the Minnesota Supercomputer Institute, and the U.S. Army, Army Research Laboratory, Army HPC Research Center. No official endorsement should be inferred.
- A1. Buoyancy-driven flow
- A1. G-jitter
- A1. Magnetic field
- A1. Melt convection
- A1. Microgravity
- A1. Three-dimensional flow